Magnetic Resonance Imaging (MRI)
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MRI stands for magnetic resonance imaging. This is an imaging tool that healthcare providers use to see inside the belly. This machine uses strong magnetic fields and radiofrequency waves to generate high-resolution pictures inside a patient’s abdomen.
Unlike other machines inthe radiology department, MRI does not use any radiation (x-rays). Certain patients, however, may not be able to undergo this test due to the presence of metal inside their body (such as a pacemaker, brain aneurysm clips or metallic implants/fragments). The technologist may also wave a wand over your body (similar to TSA agent at the airport) looking for any metal prior to entering the MRI room.
The most common uses for this test are in the evaluation of or the diagnosis of tumors (either benign or malignant) in the abdomen. It is also used in the diagnosis or evaluation of blood vessel disorders (such as arteriovenous malformations).
The test generally takes 30-60 minutes with the patient usually lying on their back. The machine generates a lot of buzzing noises during the procedure and patients are typically offered earplugs or headphones. In addition, the test often requires an intravenous injection of contrast. This contrast is very different from the contrast (dye) that is used for other radiology tests, including CT scans, angiograms and IVPs. This contrast does not contain iodine, which a number of patients have an allergy to.
Some patients -- for example, those who are over age 60 or who have diabetes, kidney or liver disease -- will need to have a routine blood test to look at their kidney function to make sure they are able to receive this contrast.
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Magnetic resonance imaging (MRI) aids in evaluation of the prostate in up to four different ways: anatomy, cellular density, blood flow and concentrations of chemicals. Each aspect in useful in a different way for prostate cancer diagnosis, and together the accuracy is better than 93%.
Your doctor will use the results of your prostate MRI for surgical planning, especially robotic-assisted laparoscopic prostatectomy. MRIs can also be used for planning biopsy and radiotherapy, as well as following up on a rising prostate-specific antigen (PSA) after prostatectomy or radiotherapy. Finally, MRI can be used for active surveillance.
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Patients with pacemakers and other metals in the body may not be MRI candidates—and anxiety may play a role for some.
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A shoulder MRI (magnetic resonance imaging) scan is a procedure that creates pictures of the internal structures of the shoulder joint by using a powerful magnet, radio waves and a computer. Muscles, tendons, bones and blood vessels may all be clearly visible on an MRI. A radiologist can then examine the pictures and use them in evaluating and diagnosing problems in the shoulder joint. Your doctor may order an MRI of your shoulder if you have any of the following symptoms:
- a mass that can be felt during a physical exam
- an abnormal finding on an x-ray or bone scan
- shoulder pain and fever
- decreased motion of the shoulder joint
- fluid buildup in the shoulder joint
- redness or swelling of the shoulder joint
- shoulder dislocation
- shoulder weakness
- shoulder pain and a history of cancer
- shoulder pain that does not get better with treatment
Shoulder MRIs are usually painless and noninvasive and can be essential tools in the proper diagnosis of common conditions including arthritis and infections, as well as injuries such as rotator cuff tears and injuries to the biceps tendon.
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It may be safe to have an MRI (magnetic resonance imaging) if you have a pacemaker, but safety guidelines must be carefully followed and appropriate resources available, and not every hospital or MRI center is set up to perform MRIs on people with pacemakers or defibrillators.
MRIs have traditionally not been performed on people who have a cardiac pacemaker or cardioverter defibrillator (ICD) due to concerns that the magnetic field will damage the device, trigger rapid pacing or cause the lead wires that connect to the heart to overheat. In addition, the device itself may cause the MR images to be suboptimal.
And while new-generation pacemakers designed specifically for MRI compatibility received Food and Drug Administration (FDA) approval in 2011, the great majority of people with pacemakers have or continue to receive conventional devices that are not conditioned for MRI.
Nevertheless, several large and small studies have focused on exploring the safety and efficacy of MRI for selected people with implanted cardiac devices. Evidence indicates that in the right clinical setting with an experienced team of cardiovascular MRI specialists, the scan can be performed safely using specific protocols. A small number of people with pacemakers, such as those with abandoned leads, may still not be able to have MRIs, even with the specific protocols.
This content originally appeared online at UCLA Health
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Men who are having magnetic resonance imaging (MRI) for prostate cancer are asked to have an enema the night before and morning of an MRI that involves the use of an endorectal coil. All men should evacuate completely so the rectum is empty during scanning. A mild sedative helps with coil tolerance. A medicine called Glucagon for antiperistalsis is also prescribed. The scan takes 30 to 90 minutes, and is longer with a full field-of-view and spectroscopy. It takes about 30 minutes to process the images, and then a quality check is done on the images.
Conventional MRI techniques, combined with the optimized signal-to-noise ratio achieved with the endorectal coil, provide high-resolution images of the prostate. These images show the prostate and the areas around the prostate so doctors can determine if the cancer has spread.
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The process of magnetic resonance imaging (MRI) can be explained as:
- Nuclei of the molecules within a human body are randomly aligned magnetically.
- When we walk into a room with a strong magnetic field, those same molecules align themselves to the magnetic field.
- For an MRI examination, a coil placed on or around you generates a pulse of energy.
- The molecules then realign with the pulse of energy.
- When the pulse is turned off or reapplied, the molecules return to their positions, creating a detectable signal.
- These detectable signals are processed by the computer into a series of images.
- Patients feel no pain during the MRI examination.
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MRI (magnetic resonance imaging) uses radio waves and strong magnets to create images of your body tissues. Many images are created during an MRI test, each focused on a different plane or "slice" of your heart. A computer combines them to create detailed pictures or movies of your heart.
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Here a few tips:
- If you have the slightest anxiety about the walls closing in, or being claustrophobic, ask if the facility is an "Open MRI." Open MRI's are usually a lot less anxiety producing if you don't like being closed in.
- Ask how long the test will take when you schedule. Don't assume that everything can be done as quickly as a chest x-ray.
- Leave jewelry home. Jewelry interferes with most imaging tests so why take a chance yours might get lost?
- Avoid wearing any clothing with metal because it will show up on the image. This means no bras with metal hooks or underwire. Wear a sports bra instead or none at all. For men, no boxers with snaps.
- Keep yourself distracted. Bring your favorite CD. Today all MRIs have sound systems and headphones or speakers.
Finally, speak up! Medical imaging departments are cold because the machines often generate a lot of heat. If you're lying on the rock hard metal table in a thin gown, it's likely you'll be cold and won't be very comfortable. Most tests can be done through blankets so make sure you ask for one (or two) if you're chilly.
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This is generally what happens after a magnetic resonance imaging (MRI) -- a diagnostic procedure that uses a combination of a large magnet, radiofrequencies, and a computer to produce detailed images of organs and structures within the body:
- You should move slowly when getting up from the scanner table to avoid any dizziness or lightheadedness from lying flat for the length of the procedure.
- If any sedatives were taken for the procedure, you may be required to rest until the sedatives have worn off. You will also need to avoid driving.
- If contrast dye is used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast dye, such as itching, swelling, rash, or difficulty breathing.
- If you notice any pain, redness, and/or swelling at the intravenous (IV) site after you return home following your procedure, you should notify your physician as this could indicate an infection or other type of reaction.
- Otherwise, there is no special type of care required after an MRI scan of the heart. You may resume your usual diet and activities, unless your physician advises you differently.
- Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.
